From: Himel, Thomas M.
[thimel@slac.stanford.edu]
Sent: Thursday, September 03, 2009 1:26
PM
To: Walker, Nicholas John;
ilc-ops-availability (alias for: Mailmaster, Mailinglist Management)
Subject: Proposed outline for
availability task force report in Albequerque and perhaps for the final written
report.
Below is my proposed outline for
the talk:
1.
Goal of the task
force (find viable solution to have good availability for SB2009 design.
Concentrated on single tunnel linac first
2.
Members/meeting
schedule
3.
3 working groups and
their assignments
4.
Machine configurations
we have studied (central DR still 6 km, long RTML transport lines, e+ source at
end of linac, linac in 1 or 2 tunnels, all other areas have accessible support
equipment)
5.
Diagram of DRFS
scheme
6.
Diagram of klystron
cluster scheme
7.
Results are preliminary
and WILL change. Mention a few items we are presently unhappy with.
8.
Availsim results of
availability as function of energy overhead for 4 configurations: 2 tunnel 10
MW, 1 tunnel 10 MW, 1 tunnel DRFS, 1 tunnel klyClus.
9.
Assumptions. There
will be many slides about this and it is the most important part of the talk.
It explains what design assumptions we made to get the above results. It will
try to explain why we made some of the assumptions and explain that we have not
necessarily optimized them yet. A partial list of these assumptions, just to
give you the flavor:
a. DRFS mod anode and DC supplies are redundant so very long
MTBF was used
b. 5 month run and 1 month long down (including recovery
time) (during which 10% of cryo systems are warmed and have all their bad
components repaired.)
c. Every 2 weeks there are 9 hours of scheduled repairs
followed by 15 hours of recovery. There is no limit on number of people used to
make repairs. Everything that can be repaired in less than 9 hours gets
repaired. This time would also be used for preventive maintenance which is not
explicitly modeled but may be needed to attain the very long MTBFs.
d. Each klystron cluster has 2 spare klystrons and
modulators that can immediately be used if 1 fails. Then the klystron or modulator
can be replaced while the accelerator is running. This simulated by giving a
very long MTBF to the klystrons and modulators.
e. Big table of MTBFs used including the comparison to other
MTBFs that we have found from other labs and the literature. I plan to color
code the spreadsheet I showed at our last meeting so it is easy to see how much
longer our planned MTBFs are than previous experience.
f.
The LLRF for klyClus
is redundant in all parts that handle signals from more than 1 cryomodule.
Simulated by very long MTBF.
g. The long high power waveguides of LLRF do not fail enough
to significantly affect the downtime. (i.e. not modeled).
h. Two people can replace a DRFS klystron in 4 hours
including transportation time. The klystrons have an MTBF of xx and nn get
replaced on an average down day.
i.
AC breakers and
transformers are lightly loaded so they get advertised MTBFs and breakers do
not trip.
10.
My intention is to
list ALL the significant assumptions and run out of time while still showing
them. This makes sure we have them documented. I will of course go over the
most important ones first.
Comments are welcome
Tom